An electronic component mounting system for mounting electronic components on boards to produce mounted boards has an electronic component mounting line which is configured so that a screen printing module for printing soldering paste on electronic components, an electronic component mounting module for mounting electronic components on boards after printing, etc. are connected (e.g. see Patent Document 1). A prior technique example described in this Patent Document has disclosed configuration in which a screen printing module, an electronic component mounting module and a reflow module are connected in series.